Magneto-electric machine



Aug. 2a, v1921s'. 1,682,086

G. MQDIGLIANgV- MAGNETO ELECTRIC MACHINE Filed Jun 1,1527.

Patented Aug. 2s, i928'.

UNITED STATES 1,682,086 .PATENT oFF-ICE.

GINO MODIGLIANI, F IVREA, ITALY, ASSIGNORTTHE FIRM ING. C. OLIVETTI &C.,

' OE IVREA, ITALY.

MAGNETO-ELECTRIC MACHINE.

Application led .Tune 1, 1927,- Serial No.

The magneto-electric machineJ ,hereafter described and forming 4theob]ect of the present invention, belongs to the. class generally calledmagnetos, generating electric 5 currents which may be used for differentobjects, but mostly for producing sparks for the ignition in combustionengines.

The present ,machine belongs to the type in which the permanent magnetsand the armature coils are fixed and the variations and reversals of themagnetic Iiux through the iron core of the armature windings areobtained by rotating parts of the.A magnetic material in such a way asto maintain the magnetic circuit permanently closed.

In the present invention, moreover, the revolving' part is perfectlybalanced and allows a light and substantial construction,

thus permitting thevery high rotational speeds now attained in modgrncombustion en es.

he rotating iron-core obtainsA in 'each revolution, four times thereversal of the direction of the magnetic-flux through the core of thearmature, and consequenty four maximums in the electroinotive force.

The articular characteristic feature of the mac 'ne is the specialarrangement of the core of the armature and of its extensions or poleexpansions. Such an arrangement allowsl a short magnetic circuit, andermits the armature core and' windings to lie ,-placed :inside thepermanent magnets, thus reducing the overall dimensions of the machineand at the same time permitting an ample extension of the surfacesfacing the air gap of the rotating and fixed magnetic cores, so that theclosure of the magnetic circuit is very ood, and stray-fluxes havingpernicious e ects onthe efiic'iency of the machine and on the life ofthe permanent magnets are reduced to a minimum, The rotating parts andthe. core ofthe armaturecambesides, be easily made out of assembledmagnetic sheet-steel stampings electrically isolatedA one from anotherand consequently free from parasite currents dispersing energy in heat.l

In the accompanying drawings, Fig; 1 is a section of the machinealongits longitudinal axis: Fig. 2 is a cross-section on the .line A-Aof Fig. 1: Fig. 3 is a per-v i spective view .of the armature core.'Figures 4, 5 and 6 are diagrammatic sections on the line A -A of.Fig. 1showing vari- 19 5,755, and in Italy September 27, 1926.

ous positions of the rotating iron-core during an entire revolution.:

The machine can -be provided with one or more horse-shoe permanent manets: the machine shown diagrammatically inthe accompanying drawing hasa single magnet 1 provided with two polar expansions 2 and 3, right andleft, bored so .as to form a cylindrical cavity in which revolves theromachine, are turned on their inside faces to the same bore of the twopolar expane parts 13 and 15 developing parallel to the shaft of thesions 2 and 3 and complete with the same the cylindrical ,cavitymentioned above.`

Extension 14 of the magnetic circuit is provided witha large hole (seeFig. 3) allow'- ing the shaft of the machine to go therethrough.

This particular arrangement provides that the bearings of the shaft beplaced laterally and on the outside of the group forming the magneticpart of the machine. In such a way the shaft can be extended on bothsides of the engine, its bearings can be placed in a position easy to bereached and inspected and at one end of the shaft can be easily fixedthe coupling ange and at the other can be arranged the parts controllingthe circuit breaker and the 4current distributor which, as known, existin all magneto-electric machines used for ignition in internalVcombustion motors.

All parts forming the armature jiist described are held together and tothe base of the vmachine with proper connections and means, which forclearness-sake are not shown in the drawing. The rotating part whichproduces, with its motion, the variations and reversals of the magneticflux across the armature, is formed by a shaft 4 oflionmagnetic'mate'rial, carried by two bearings 5 and 6 on4 which,between proper flanges 7 8 and 9, also of nonmagiietic material, areheld two circular segments 10 and 11 vof magnetic material, preferablylaminated,-whi'chv due to their relatively great i length, are securedto lthe shaft by the interrotating core can be replaced by any otherVobtaining` the same result of giving. a unit resisting distortion andcentrifugal forces.

The above described arrangement of the magnetic parts obtains a veryshort magnetic circuit, while, owing tothe length of the parts 13 and 15of the fixed pole members of the armature, ofthe pole-expansions 2 and 3of the permanent magnet and of the segments 10 and 11 of the rotatingpart, the surfaces of the fixed and moving magnetic' parts facing eachother through the air-gap, are very ample and thus stray-fluxes causedby said air-gap are reduced to a min- As clearly shown in section Fig. 2the circular segments 1'0 and 11 forming the rotating part ofthe core,cover an angle somewhat greater than the angle between the polarexpansions 2 and-3 of the permanentmagnet. This is necessary in order,to always keep the magnetic circuit practically closed.

To understand the working of the machine reference is directed to Figs.2, 4, 5 and 6.

In the latter the variousparts are marked with the same numbers in alligures viz: 10 and lllare the circular segments forming therotating-core, 2 and 3 the polar' expansions of the permanent vmagnet 1ande 13 and 15 the polar expansions of the armature-core.

Supposing that'the N pole of the magnet be vat the'polar expansion 2,that the magnetic flux willv be directed north-south, when the rotatingcore is in 'the position shown in Fig. 2, the magnetic iux passesdirectly from polar expansion 2 tof3 across the 4two cores 10 and 11. Insuch' a position the magnetic flux does not go through armature core 12(Figs. 2 and 3) but, as soon as the rotating core'having revolvedthrough a small angle in the direct-ion of the arrow, attains theposition shown in Fig. 4f, the magnetic flux passes from polarexpansion2, across segment 11 to the polar expansion 15 of the armature core andthrough the same, to its polar expansion 13 and across' segment 10 topolar expansion 3 (south) of the magnet.

` Thus the armature core is crossed by a4 flux entering fromfpolarkexpansion 15`andleaving at'polar' expansion 13. q Proceeding in therotation to the posimeans@ i' tion shown in Fig. 5, the magnetic uxthrough the armature-core falls to zero as it can go throughfrom polarexpansion 2 v I to polar expansion 3 directly, subdividing in twobranch-fluxes offered by the rotating segments 10 and 11 and by thepolar expansions 13 and 15 of the core of the armature, cross-ways. Y

' Proceeding further in the rotation and coming to the position shown inFig. 6 the magnetic iux passesfrom polar expansion 2 through segment 11to polar expansion 13 and through the armature core, then from its otherpolar expansion 15 through segment 10 to polar expansion 3 (south) ofthe magnet. In this way the armature-core is crossed by a iux enteringfrom polar expansion 13 and going out at `polar expansion 15, that is inthe opposite direction as previously shown.

Proceeding in its rotation, the rotating core after one half revolutioncomes in a position symmetric to the starting position (Fig. 2) in whichhowever the rotating segment 10 assumes the position in which.segment 11was at the start and vice versa.

So in one half revolution two reversals of the magnetic iux are obtainedin the core of the armature, i. e. twomaximums of current in the windingand, proceeding further in the rotationy for another half revolution,-

-right to the starting position, two other maximums will be obtained,that is four in one revolution.

In case the machine should be used for the ignition of internalcombustion engines, it will be, as usual, provided with two windings,one low-tension and onehigh-tension,

and with a circuit-breaker on the primary or low-tension circuit, ywhich.will break the circuit at the moment the.. electromotive force goesthrough a maximum, thus obtaining the immediate increase in voltage inthe secondary circuit and consequently the sparks in the sparking plugsof the engine as practiced with all ignition magnetos.

What I claim is: 1. vA magneto electric machine comprising a fixedarmature, a fixed magnet, fixed core ends, for the armature extendinginto two polar expansionsl provided sov that one of them lies above theaxis of rotation of -the machine, the'other below the same axis, and both expansions being formed in their. insidesov as to form a cylindricalcavit a.

revolving part /rotating in the cavities w ose-y magnetic core'jconsists of two (circular, seginsulated magnetically one fromanother, a

the parts forming the armature, that is the g core expansion Aand itspolar ex ansions, f'lie -ments lconnected mechanically together but"nonmagnetic shaft"`for the revolving part,

ture to its lower end, and being provided with a large a rture allowingtheshaft to go therethrong 2. A magneto elect-ric machine comprising afixed armature; a permanent magnet; a revolving part comprising amagnetic core consisting of two circular segments mechanicallyconnectedtogether and isolated magnetically one from the other; anonmagnetic shaft for said revolving part; and a fixed core bearing thearmature winding provided on the inside of the ermanent magnet andconnected to the p0 e-shoes of the armature by two prolongations, one ofthe pole-shoes extending from right to left, the other from left torightparallel tothe axis of rotation of the revolving part, and one ofthese pole-shoes being placed relative to the axis of rotation, on thesame side 4as t e fixed core, while the other ,pole-shoe isdiametrically opposite and joined with the core by one of theprolongations'which is shaped in such a manner as to allow the passageof the shaft which bears the rotating magnetic parts.

In testimony whereof vI aiix my signature.

GINO MODIGLIANI. A,

